The present invention generally relates to transfer control devices for reproducing transducers in rotary recording medium reproducing apparatuses, and more particularly to a transfer control device capable of switching over to perform a high-speed transfer, an intermediate-speed transfer, and a normal-speed transfer of the reproducing transducer, by use of a small number of output ports of a micro-computer.
Systems have been realized in which a recording system forms pits in accordance with information signal being recorded along a spiral track on a flat rotary recording medium (hereinafter referred to as disc), without forming a groove therein, and a reproducing stylus traces over along this track to reproduce the recorded information signal in response to variations in the electrostatic capacitance in a reproducing system.
In this system, since no groove is provided on the disc for guiding the reproducing stylus, pilot or reference signals are recorded on or in the vicinity of a track of the information signal, such as a video signal, on the disc. Upon reproduction, the reference signals are reproduced together with the video signal. Tracking servo control is carried out so that the reproducing stylus accurately traces along the track in response to the reproduced reference signals.
In the above described system, since the disc surface is flat having no grooves for guiding the reproducing stylus, the reproducing stylus can be transferred in a rapid manner towards the radial direction of the disc unto a predetermined position without whatsoever damaging the reproducing stylus or the disc. That is, a so-called random access operation and the like can be performed in the above system. In the random access operation, the reproducing transducer is initially transferred at a high speed, then the transferring speed is switched over to an intermediate speed when the reproducing transducer reaches a position in the vicinity of an intended position, and the transfer of the reproducing transducer is finally stopped when the reproducing transducer reaches the intended position. The above random access operation is performed while addresses on the disc are detected. Moreover, during normal reproduction, the reproducing transducer is transferred at a normal speed. Accordingly, as a transferring speed for the reproducing transducer, there are the following three kinds of speeds.
(1) Normal transferring speed
(2) Intermediate speed: 250 times the normal transferring speed, for example.
(3) High speed: 1200 times the normal transferring speed, for example.
Furthermore, the normal transferring speed is used for a normal reproducing mode through a 65-times speed reproducing mode. During normal reproducing mode, the reproducing transducer performs reproduction in terms of one track. In addition, during 65-times speed reproducing mode, for example, the reproducing stylus is successively kicked to an adjacent track at 64 positions for one revolution of the disc. During the above modes in which the reproducing transducer is transferred in a normal manner, a feed pulse is supplied to a feed motor every 32 tracks of the disc (every 32 revolutions of the disc during normal reproducing mode, and every 16 revolutions of the disc during 2-times speed reproducing mode, for example), regardless of multiple speed reproducing mode, to transfer the reproducing transducer.
A control signal is obtained from a micro-computer according to the mode of the transferring speed of the reproducing transducer, and supplied to a feed motor drive control circuit to perform a rotational speed control operation with respect to the feed motor.
However, various kinds of control signals were conventionally used to perform the above speed control operation. Therefore, a plurality of output ports of the micro-computer were used for producing the various control signals.